Substrate Electronics Dominate the Rate of Reductive Dehalogenation Promoted by the Flavin-Dependent Iodotyrosine Deiodinase

Authors

Anton Kozyryev
Daniel Lemen
Jessica Dunn
Steven E Rokita

Publication Date

4-4-2023

Journal

Biochemistry

Abstract

Iodotyrosine deiodinase (IYD) is unusual in its reliance on flavin to promote reductive dehalogenation of halotyrosines under aerobic conditions. Applications of this activity can be envisioned for bioremediation, but expansion of its specificity requires an understanding of the mechanistic steps that limit the rate of turnover. Key processes capable of controlling steady-state turnover have now been evaluated and described in this study. While proton transfer is necessary for converting the electron-rich substrate into an electrophilic intermediate suitable for reduction, kinetic solvent deuterium isotope effects suggest that this process does not contribute to the overall efficiency of catalysis under neutral conditions. Similarly, reconstituting IYD with flavin analogues demonstrates that a change in reduction potential by as much as 132 mV affects

Keywords

Humans, Iodide Peroxidase, Electron Transport, Catalysis, Organic Chemicals, Flavins, Kinetics, Substrate Specificity, Oxidation-Reduction